BMW M10

BMW M10
BMW M10 engine inside
Overview
Manufacturer	BMW
Production	1962–1988
Combustion chamber
Configuration	SOHC Straight-4
Chronology
Successor	BMW M40

The BMW M10 is a straight-4 SOHC piston engine produced from 1962 to 1988 with displacements ranging from 1499 cc to 1990 cc. It was first released in the New Class sedans and began to be phased out following the introduction of the M40 engine in 1987.

The engine was a commercial success for the Bavarian carmaker, with over 3.5 million produced in almost three decades across many BMW models. It has a forged crankshaft, counter balance weights, five main bearings and a chain-driven camshaft. The block is made from cast iron and the head is made from aluminium.

It was also used as the basis for the turbocharged BMW M12 motorsport engine, which for instance was used by Brabham-BMW in the Formula One racing series.

The engine was designed by engineer and race driver Baron Alex von Falkenhausen. In the late 1950s, he was asked to design a small-displacement (1.3 L) engine, but felt that this would be insufficient for the company's future needs. Therefore, he convinced BMW that the capacity should be 1.5 L instead and he designed a block that could be expanded to 2.0 L in the future. BMW M10 Engine utilized Hemispherical combustion chamber in 8 valve arrangement.

The engine was initially known as the "M115" (the last two digits representing the 1.5 litre capacity). Over the years, variants of the engine were given various codes (most of them starting with "M1..." and the remaining digits relating to the capacity). In 1975, the engine became known as then "M10", then in 1980 it was given the standardised BMW engine code of M10B18 (where "M10" represents the series and the "18" represents the 1.8 litre capacity).

The M115 and all related engines have become retrospectively known as the "M10" family.

The 1.5 L (1499 cc/91 in³) M115 produced 75 hp or 80 hp (56 kW or 60 kW), depending on the state of tune. Bore is 82 mm (3.2 in), stroke is 71 mm (2.8 in). Lower power models use an 8:1 compression ratio, while higher power models use a ratio of 8.8:1. Fuel is supplied via a Solex 38 PDSI carburettor.